Telephone system



F. M. StOUGH. TELEPHONE SYSTEM. APPLICATION FILED ocr. 18, 1913.

1,4029%, Pa tented Jan. 10,1922.

2 SHEETS-SHEET I.

IN VENTOR'.

W 23 I v FRANK M..SLOUGH M his ATT F. M. SLOUGH. TELEPHONE SYSTEM.

APPLICATION FILED OCT, 18, I913.

2 SHEETS-SHEET 2.

INVENTOR. W v FRANK M..SL.OUG/' l H/s' ATT v PatentedJ 111. 10, 1922.

starts" rarest @Fhlfitt.

i FRANK M. SLOUG-H OF ELYRIA, OHIO, ASSIGNOR, BY IvIESNE ASSIGNIVIENTS,TO

EwTROIdBERG-CARLSON TELEPHONE MFG. 00., OFROGHESTER, NEW YORK,

a conrona'rionor new roan.

'rnnnrnonn SYSTEM.

naoasos.

Specification of Letters Patent.

Patented Jan. 16*, 1922.

Ahplicationfilcfl Octoberl 1913: Serial 795323;

To all whom it may concernr I Be it known that I, FRA K M. SLoUGH, acitizen of the United States, residin Elyria, in the county of Lorainand tate of C hio have. invented certain new and useful Improvements inTelephone Systems; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame. 1 p f 1 My invention relates to telephone systems, and moreespecially to centralenergy sys; tems, in which a plurality of telephonelines lead from subscribers stations to a main station where apparatusis providedto connect such lines. together. In general, cord circuitsare employed for connecting the lines together, the lines and the cordsbemg provided with complementaryswitching apparatus to connect theends'of the cords to the lines. After the termination of theconversation, the operator is automatically signalled of thetern'iination but frequently the disconnections are not madeimmediately, owing either to the inattention or the engagement of theoperator. Durmg this period the lines are tied up to the cord,preventing their use for other connections. One of the objects of myinvention is to provide means for releasing the lines from the cordemployed in a conversation as soon as that conversation has terminated.

Another object is to provide means for accomplishing this firstnamedobject and placing such means under the control of the switchingapparatus employed for connecting the cord to a line.

Another object is to accomplishthe ab'bve' operators set to the cordAnother object of my invention is to providexwhat has come to belmown assecret listening in connection with the automatic disconnectingapparatus, placing the secret listening controlling, apparatus under thecontrol of the automatic disconnecting apparatus so as to: prevent thereturn of the after the disconnection is made. i i

Another object of my invention is to place the control of theringingcurrent under the called subscriber, and especially to place both theautomatic disconnecting apparatus and the ringing apparatus under thecontrol of the callinsubscriber. Other 0 jects of my invention and theinventionitself willgbe better understood from a description of theparticular embodiments of my invention illustrated in the'drawings.

"Fig. 2 is a diagram illustrating a more complicated form of circuit.

Referring now to the embodiments of my invention illustrated in thedrawing and first tothat illustrated in Fig. 1, at'A I show atelephoneline. B indicates a substation connected on this 'line,thesubstation set in cluding a tra'nsmitterC, a receiver D and switch Econtrolled by the weight of the receiver. This form ofapparatus is Wellknown and needs no particularly description. The line is connected byconductors 1 and 2 to the main station F, Where it terminates in aswitch element G, here shown as a jack, consisting ofa plurality ofcontacts 3, 4 and 5. The line apparatus of the line A is illustrated atHand consists of a wellknown "form of line and cut-oil relays. Thisapparatus constitutes no part of my invention and any suitable form maybe used. At the station F connecting apparatus is employed forconnecting .the lines together,

here shown as 'a cord circuit, the talking strands of Whichareillustrated at I and J. In the 'formshown a third strand is employed andillustrated at K. The strands of the cord circuit terminate inswitchingele ments complementary to the switching elements employed on the lineand illustrated, for example," at G on the calling line. In the formshown the switching elements on the cord circuit consist of plugsillustrated at L and M; The plug L consists of a plurality of contacts,shown at 6, 7, and '8 and in the plug M at 9, 10 and 11.

' Any suitable number of substations may be connected on any of thetelephone lines. On the lineN, I have illustrated four substations at O,P, Q and R. Each'substation is provided with a talking and signalingset,"

such as illustrated diagrammatically atO. The line N leads to thecentral station'and terminates thereat in asuitable switching element,such as a jack S,-here*shown' as con-' receiver D is removed from theswitch-hook,

whereupon theswitch E- isclosed and the lamp 15 operated in the usualmanner. Seeing-the operatio'n'of the lamp 15, the opera tor at F insertsthe plug L into the jack G,

connectingone end of the cordto thejcalling line. A circuit, will be.completed from 16- through 17 1 8- 19 20' relay 21'. 8 57- 22- togroundat 23, completing a circuit and energizing therelays 21. and 22.

The relay 22 cuts oil the line signal and line relay from the .line inthe usual manner.

Belay 21 closes the switch 24 -25 and completes the circuit of thesupervisory signaling lamp 26 through a conductor. 27 to a backcontact28 of the tip supervisory relay 7 29. This relay will beenergized, owing'to the fact that the substation circuit at B is closed,a circuit being traced from the battery 30- through the left hand end ofthe talkingstrands of the cord circuit and over the calling subscribersline, The operator operates the listening springs U, connecting hertelephone set V to the talking r in order that the relays 31 and 32 maybe de strands and communicates with the subscriber at B, learningthatit, is the subscriber at O that is wanted. After testing the line andassumin that it is found idle, the plug M is inserte' into the jack S,completing a circuit through the relays 31, 32 and 33. Relay 31 cuts offthe line signal and line relay from the called line. The relay 32attracts the armature 734,.closing a switch 3435 and completing thecircuit of the supervisory lamp 36, whichburns as long .as

the called line is open. Relay 33 will not be energized at this time,sincethe relay 29 has been energized, completing a shunt 37 through thecontacts 3839 around the winding of the relay 33.

I make therelay 33 of higher resistance,

energized when the winding of the relay 33 is connected in the circuitof the relay 31, and also in order that the batteryv potential on thesleeve 12 of the ack may be sufiibecause the higher resistance of'thisrelay connected unshunted ln'circult with winding 31 and sleeve 12 willreduce the current fiow through this circuit. Y

When the called subscriber responds, the

relay 40 will be energized from the battery cover the right hand end ofthe cordcircuit and the line of the called subscriber. relay willattract the armature 41, closing a This switch 41.42 and completing asecond shunt 43 about the winding of the relay 33. The switch 41- 414will be opened,.retiring the supervisory signal. 36. The conversationhaving continued to. a termination, the subscribershang up f theirreceivers, interrupting the continuity of the lines and deenergizing therelay 29 and 40, interrupting the shunts about the relay 33,whichis-ener gized over a circuit .60- 61- 33 62 32 63- 11- 12-.- .3164. 'As stated, the introduction of the resistance 33 in this circuitreduced the current to such an extent that the relays 31 and 32 releasedtheir conditions. The relay 33, however, was

.armatures, restoring the called line. relay. and line and supervlsoryslgnals to normal energized, attractingits armature 65, closing a switch66 in a circuit including the electromagnets 67 and 68, wh1ch circuit'ls67 70- 68- 71, and a second circuit through the disconnect lamp 72 toground 73. The operation of this lamp indicates to the operator that theautomatic disconnection has taken place. The relay 67 was energized overthis circuit, attracting its armatures 53 and 56 and opening theswitches52-53 and 5657, each shown in the talking strand of the cordcircuit, and

disconnecting the plug M from the inter: mediate portion of the cordcircuit. The relay 68 was also energized, attracting its armatures 51, 51 and 20, opening the switches 50'51 and and disconnecting the plug Lfrom the intermediate portion of the cord circuit. The switch 19--2O wasalso opened in the circuit of the relay 21, whereupon the line relay andsignaling apparatus of the calling line was restored to normal. In thiscondition both lines are released and may be used forother connectionsand the battery potential of the contact 12 of jack S being greatlyreduced bytheinterposition of the high resistance relay 33 in itscircuit, the line will not test busy. "Also, as the circuitof thecorresponding contact 5 of the jack G is opened at 19-20 the callingline will also indicate a non-busy condition upon being called.

Assuming that the called subscriber at O Wise, the operators set iyonnever responds and that the subscriber B for some reason, such asimpatience, hangs up his receiver, under these circumstances theautomatic disconnecting apparatus will be operated, since the shunt e8will never have been closed about the relay 33, owing to the failure ofthe called subscriber to answer and tie shunt 37 completed will beinterrupted when the calling lineis opened.

Referring now to Fig. 2, l have illustrated at a. a diil'ercntial relaycontrolling the connection of the operatorsset to the cord circuit andthe disconnection of the same therefrom. This apparatus is pre viouslyknown and is not a portion of my invention. ll hen the plug insertedintothe jack of the calling line, a circuit is completed through the winding2') of the relay and the battery 0, energizing the niac net andattracting the arrnatures 100 and 101 and connecting the operators set Zto the cord circuit-x1 place the a under the control. or" theautomaticdisconneet o; apparatus, for example, by -ilacinp; a suit-11103 under control of relay 102, so that the switch 103 in the circuit ofthe winding 3) Will be interrupted when the automatic dis connectingapparatus is ooeratocl; other a e re; onnected to the calling lineagsoon as he called subscriber hung up. At X l have illustrated sourcesof energy for supnlyinQ one. operate the suhstationsi apparatus. Suchapparatus 13 connected to theline over suitable conductors, such as 106,107 and'l08.

ing a switch 109-110 under centre relay 11L This is especiallya insystems employing automatic 1 cause when calling subscribe which hesometimes does Withofor the called subscriber to ZUISFFEE' niaticringing current is automatically To moved from the line. This will beaccomplished in the system illustrated in as follows:

W hen the relay 33 is eneroized in the Way described in Fig. l. a circit will be completed as follows: 112l18-11i 115 11c- 117 11.1- 118*102-; 119,, energizing the relays 111 and 102, disconnecting the plug'32 and g from the in'terniedjc' tion or" the cord circuit, disconnectnsource 01" ringing current X from the p g at 109 and 110 andinterrupting the cuit of the Winding 7) of the magnet (a 108-12O.

l do not WlSll to be limited to the details of the embodiments of myinvention illustrated, these being shown simply for the purpose ofdescribing the invention.

I claim 1.. In a telephone system the combination of a main station, aplurality of substations .7 Alt? 21. 34

telephone lines connecting the substations to the main station. andterminating in jacks at the main station, a cord circuit at the mainstation terminating in plugs adapted to be inserted in said jacks forconnecting the lines together a low resistance relay associated with oneof the lines, a high resistance relay associated with the cord circuit,a source of current, means including a pit and jack switch forconnecting said relays i C1ICu1tWl l'1 said source fcurrent,

e when said -one system the combination ion and a rality oi sub nc linesfor connecting the he inain station, a cord circuit tion torcoiectingtelephone means controlled by the subautomatically isolating the sor? the cordcircuit from the ry apparatus in the 1 p- Alt; $3185.

corn circutc rolled by the called subscriber and means operativeindependently of said apparatus controll ng said interrupti means. i

u, in telephone system, the conioination 01 a 119,111 station and aplurality of subfor connecting the connecting teleler, supervisorysignaling L ctedto the strands of the control ed by the calledsubscriber and s operative independently of said suyisory apparatus forautomatically disconnecting he plugs of the cords "from the terniediateportion thereof W enthe subibers Whose substation sets have beenconnected to the cord have been restored to normal.

i one system the combination 1 S'illllcll and a plurality oi subonstelephone lines for connecting the substations to the main station, acord circuit the-main station for connecting telephone linestogethersupervisory signaling apparatus connected, to the stranos of the i lcontrolled t e calling subscriber 1 means open" I "risory apparatus forautomatically disthe plugs of the-cores from the thereof W en thesubtion sets have been con been, restored to enendently of said 5. In atelephone system, the combination o-t-a main station and a plurality ofsubstations, telephone lines connecting the subscriber for effectivelyeliminating said elec tromagnetic means from said circuit and meanscontrolled by the called subscriber for effectively eliminating saidmeans from said circuit, each of said eliminating means beinginoperative t eliminate said electromagnetic means from said circuitwhen the talking bridge at the substations is interrupted.

6. In a telephone system, the combination of a main station, a pluralityof substations, telephone lines connecting the substations to the mainstation, a cord circuit at the main station for connecting said linestogether, means for automatically interrupting the talking strands ofthe cord circuit,

electromagnetic means controlling said interrupting means, a circuitforsaid electromagnetic means, means controlled by the called subscriberfor effectively eliminating rupted.

saidelectrom'agnetic means from said circuit, said eliminating meansbeing inoperative to eliminate said electromagnetic means from saidcircuit when the talking bridge at the calling subscribers station isinter- 7. In a telephonesystem, the combination of a main station, apluralityj'of sub-' stations, telephone lines connecting the substationsto the main station, a cord circuit at the main station for connectingsaid lines together, means for automatically interrupting the talkingstrands of the cordcircuit, electromagnetic means controlling saidinterrupting means, a circuit for said electromagnetic means, meanscontrolled by the calling subscriber for effectively eliminating saidelectromagnetic means from said circuit, said eliminating means beinginoperative toeliminate said electromagnetic means from said circuitwhen the talking bridge at the called subscribers station is interrupted8. In a telephone system, the combination of a main station, a pluralityof substations, telephone lines connecting the substations to the mainstation terminating in switch elements at the main station, a cordcircuit at the main station for connecting telephone lines togetherterminating in switch ele-.

1 ments adapted to co-operate with the switch 7 elements in which thesubscribers lines terminate, means for disconnecting the switch elementsof the cord from the intermediate portion of the .cord, a devicecontrolling said means, a circuit for said device and meansforefiectively eliminating said device from'said circuit controlled by asubscribers substation apparatus. 7

9. In a telephone system, the combination of a main station and a.plurality of substations, telephone lines connecting the sub stations tothe main station, a cord circuit for connecting'said telephone linestogether, means for automatically interrupting the talking strands oithe cord circuit, electromagnetic means controlling said interruptingmeans, a circuit for said electromagnetic means and a shunt about saidelectromagnetic means controlled by a subscriber.

10. In a telephone system, the combina- 'for connectin said tele honelinesto ether b c a means for automatically interrupting the talkingstrands or' the cord circuit, electro magnetic means controlling saidinterrupting means, a circuit for said electromagnetic means, aplurality 01' shunts about sa d electromagnetic means each under thecontrol of the subscribers.

12. In a telephone system, the combination of a main station and aplurality of substations, telephone lines connecting the substations tothe main station, a cord cir- 'cuit'at the main station for connectingthe telephone lines together, supervisory'apparatus connected to thestrands of the cord circuit controlled by a subscriber, means forinterrupting the talking strands of the cord circuit, electromagneticmeans controlling said interrupting means, a circuit for saidelectromagnetic means, a shunt about said electromagnetic means, and aswitch including contacts in said shunt controlled by the supervisoryapparatus,

13. In a telephone system, the combination of amain station and aplurality of substations, telephone lines connecting the sul stations tothe main station, a cord circuit at'the main station for connectingtelephone lines together, means for automatically interrupting thetalking strands of the cord circuit when the subscriber whose talkingapparatus has been connected to the cord circuit has disconnected histalking apparatus therefrom, a talking set at the main station and meanscontrolled by said interrupting means controlling the connection of theoperators set to the talking circuit.

14. In a telephone system, the combination oi a main station and aplurality of substations, telephone lines connecting the substations tothe main station, a cord circuit at the main station for connectingtelephone lines together, means tor automatically interrupting thetalking strands of the cord circuitwhen the subscriber whose talkingapparatus has been connected to the cord circuit has disconnected histalking apparatus therefrom, a talking set at the main station, andmeans for automatically connecting the operators set to the telephoneline controlled by said interrupting means.

15. In a telephone system, the combination of a main station, a callingand a called line terminating at said station, a subscriber on each ofsaid lines, a cord circuit having separate talking and operating strandsat the main station, plug and jack switching means for connecting saidtalking and operating strands to each of the lines, supervisory means inthe answering end of the cord, in cluding a supervisory relay, automaticmeans for opcratively disconnecting all of the strands of the cord fromthe calling line when the calling subscribers station apparatus isretired, said automatic disconnect means being initially controlled bythe supervisory relay and subsequently maintained by switching means forconnecting one of the strands of cord to the called line.

16. In a telephone system, the combination of a main station, a callingline termihating at the main station in a switchboard jack, a callingsubscribers substation set upon the calling line, a called lineterminating at the substation in a switchboard jack, a called substationset upon the called line, a cord circuit at the main station includingseparate talking and operating strands, plugs at the main station inwhich the cord circuit terminates and which are adapted to be insertedinto the jacks of the calling and the called line to establishcommunication between the calling and the called subscriber over thelines and the talking strands of the cord circuit, relay mechanism atthe main station having contacts in the talking and. operating strandsassociated with the calling line. supervisory means in the an sweringend of the cord circuit including a supervisory relay, a circuit for thefirst named relay controlled by said supervisory relay, a third relay inthe operating strand of the calling end of the cord also controlling thecircuit oi said first named relay, a circuit for the third named relaylocalto the main station and including contacts of the jack of thecalled line and thecalling plug.

17, I a telephone system, the combination of a main station and aplurality of substations, telephone, lines leading from said substationsto the main station, a cord circuit having separatetalking and operatingstrands at the main station for connecting two telephone lines together,co-operating switching means for connecting the cord circuit to thetelephone lines, means for operatively disconnecting all of the strandsleading to the answering switching means from the corresponding strandsof the cord circuit, said means maintained under the sole control of theswitchingmeans at the'other end of the cord and a disconnect signaloperated at the time of disconnection, likewise maintained.

18. In a telephone exchange system, subscribers lines having switchingterminals, operators connecting circuits having co-opcrating switchingterminals, said opera-tors connecting circuits including two talkingstrands and a third strand, and means controlled by the subscribersthrough said circuits for disconnecting both talking strands from bothsubscribers and disconnecting said third strand from one of saidsubscribers without disconnecting it from the other. i y

19. In a telephone system, the combination of a main station, aplurality of substations, telephone lines for connecting the substationsto the main station, a cord circuit at the main station for connectingtelephone lines together, plug and ack switching means for connectingthe cord circuit to the telephone lines, a source of current, a cut-offrelay in a line circuit, a high resistance relay in the cord circuit,current conductors including a plug and ack connecting the highresistance relay and the cut-off relay in circuit with said source ofcurrent and means to prevent the energization of one of said relayswhile the other is energized.

:20. In a telephone system, the combination of a main station,aplurality of substations, telephone lines for connecting thesubstations. to the main station, a cord circuit at. the mainstation forconnecting telephone lines together, plug and jack switching means forconnecting the cord circuit to the telephone lines, a cut-off relay inthe line circuit, a high resistance relay in the cord circuit in circuitWith said cut-oil relay and means to prevent the actuation of one ofsaid relays While the other is actuated.

21. In a telephonesystem, the combination of a main station, a pluralityof substations, telephone lines for connecting the substations to themain station, a cord circuit at the main station for connectingtelephone lines together, plug and jack switching means for connectingthe cord circuit to the telephone lines, line signal apparatus normallyconnected to the line, a'cut-olf relay controlling said, line signalapparatus, a high resistance relay associated with the cordccircuit,means for supplying energy to said relays and subscriber controlledapparatus for causing thede-energization of the cut-off relay and theenergization of the high resistance relay.

22. In a telephone system, the combination of a main station, a callingline leading to the main station, a called line leading to the mainstation, substation apparatus on said lines, a source of currentassociated with said system, a cord circuit at the main station havingseparate talking and operating strands, plug and jack switching meansfor connecting each end of the cord to a telephone line, apparatus forautomatically disconnecting all of the talking strands of the cordcircuit from one ofthe connected lines, means including a callingsubscribers set controlling said automatic disconnecting ap- V paratus,said automatic interrupting apparatus being inoperative until thecalling subscriber retires, and mechanism under the control of the plugand jack switching means associated with the other connected line formaintaining said automatic interrupting apparatus until the plug of thelast mentioned plug and jack switching means is withdrawn from thecorresponding jack.

In a telephone system, the combination of a main station, a calling anda called line terminating at said station, a subscriber on each of saidlines, a cord circuit having separate talking and operating strands atthe main station, plug and jack switching means for connecting saidtalking and operating strands to each of the lines, supervisory means inthe answering end of the cord, including a supervisory relay, automaticmeans for operatively disconnecting all of the strands of the cord fromthe calling line when the calling subsoribers station apparatus isretired, said automatic disconnect means being initially controlled bythe supervisory relay and subsequently maintained by switching means forconnecting an operating strand of the cord to the called line;

'24-. A telephone system comprising subscribers lines having switchingterminals, link conductors having co-operating switching terminals, linesignals for said lines, cut-' cit relays for said line signals, a localcircuit associated with each end of said link conductors, each localcircuit including a cooperating pair of switching terminals, one of saidcut-off relays and a source of current, and means controlled by one ofthe subscribers for decreasing the flow of current to a predeterminedpositive value in one of said local circuits to release one of saidoutoff relays, whereby the subscribers may regain contlOl'of their linesignals.

25. A telephone exchange vsystem including telephone lines extendingfrom substations to an exchange, a cord circuit to connect saidsubstations and comprising separate talking and operating strandcircuits individ ual to the respective cord circuit for callingandcalled lines, a disconnect signal circuit associated with said cordcircuit during an established connection therewith and closed by theopening of said talking and operating strand circuits under the combinedcontrol of both calling and called substations.

26. In a telephone system comprising subscribers lines terminating at acentral ohice, link conductors thereat having cooperating switchingterminals, line signals for said lines, cut-cit relays for said linesignals, a local circuit associated with each end of said linkconductors, each including a co-operating pair of said switching tersminals, one of said cut-off relays, a source of current and anotherrelay and apparatus controlled by the subscribers in the operation oftheir switch hooks for increasing and decreasing the flow of currentthrough said local circuits, said cut-off relays restor ing the linesignals to the control of the subscribers when said apparatus isoperated to decrease the current in the local circuits.

27. A telephone system comprising subscribers lines terminating in. acentral oflice, line signals thereat for said lines, link conductors atsaid oflice for interconnecting said lines, a pair of relay windingsassociated with the one end of said link conductors, one of which isnormally short-circuited when said link conductors are associated withone of said lines, a cut-off relay for the line signal of the said lineenergized over a circuit including the non-shortcircuited winding ofsaid pair of relay windings, and electromagnetic means controlled by thesubscriber in the operation of his switch-hook for removing the shortcircuit of the short-circuited windingof said pair of relay windings forreleasing said cut-off relay, whereby said subscriber may regain controlof his line signal.

28. In a telephone system, the combinationoi a main station, a pluralityof telephone lines leading thereto, a cord circuit including a thirdstrand for connecting said telephone lines together, switching mechanismfor connecting the cord to a line and electromagnetic means without thetalking circuit for automatically disconnecting such switching mechanismfrom the cord circuit when a connected subscriber retired his substationtalking set, said last named meanscontrolling the third strand of thecord.

29. A telephone exchange system, including telephone lines extendingfrom sub-stations to an exchange, link connectors to connect saidsub-stations and comprising separate talking and operating strandcircuits individual to the respective link connectors for calling andcalled lines, means under the control of apparatus at the callingandcalled substations to open the talking and operating strand circuits ofsaid link connectors connected to their lines, a high resistance circuitincluding the magnetic winding of a disconnect relay, and a disconnectsignal operated by said relay when said link connector strand circuitsof both calling and called sub-stations are so opened.

30. In a telephone system, a main station, a plurality of substations,telephone lines leading "from said main station to said substations,line signal apparatus associated with each of said telephone lines atthe main station, a cut-off relay associated witheach line and adaptedto remove said line signal apparatus from the telephone line, a cordcircuit at the main station containing separate talking and operatingstrands, a plug and jack switch for associating the talking strands ofthe cord circuit with the talking strands of the calling line and forassociating the cut-off relay of the line circuit with an operatingstrand of the cord circuit, a plug and jack switch for associating thetalking strands oi the cord circuit with the talking strands oi thecalled line circuit and also to associate the cut-cit relay of thecalled line with an operating strand of the cord circuit, a relay in thecord circuit under the control or one of the connected substations, adisconnect relay at each end of the cord circuit adapted to operativelydisconnect each of the connected line circuits and each of the cutoffrelays from the talking strands and operating strands of the'cordcircuit, and a high resistance relay in the operating strand leading toone of the plug and jack switches, said high resistance relay beingoperated when the cut-off relay con nected in the same operating strandis operatively disconnected, said high resistance relay controlling adisconnect signal.

31. A telephone system, comprising subscribers lines having switchingterminals, link conductors thereat having co-operating switchingterminals, line signals for said lines, cut-oil relays for said linesignals, an operators telephone associated with said link conductors, arelay for connecting said operators telephone to said link conductors, alocal circuit associated with each. end of said link conductors, eachlocal circuit ineluding a co-operating pair of switching terminals, oneof said cut-oft relays, a source of current and a. winding of saidoperators connecting relay and apparatus controlled by the subscribersin the operation of their switch-hooks :tor increasing the resistance ofsaid local circuit associated with one end of said link conductors, saiddecreased flow of current permitting the release of said cutoff relaysto restore to the Subscribers the control of said line signals andsimultaneously disassociating said operators connecting relay from saidcut-oil relays.

32. A telephone system comprising sublink conductors and meanscontrolled by the operation of. a subscribers switch-hook for removingthe short circuit from said high resistance relay winding to releasesaid outoff relay and said second relay, whereby the subscriber mayregain control of his line signal and the operators set is preventedfrom being connected by said second relay to the link conductors.

33. A telephone exchange system including telephone lines extending fromsubstations to an exchange, link conductors to con nect said substationsand comprising separate talking and operating strand circuits individualto the respective link conductors for calling and called lines, adisconnect signal. circuit associated with said link conductors duringan established connection therewith and closed by the opening of saidtalking and operating strand circuits under the combined control of bothcalling and called substations.

84. A telephone exchangesystem, including telephone lines extending fromsubstations to an exchange, link conductors to connect said substationsandcomprising sepa= rate talking and operating strand circuitsindividual to the respective link conductors for calling and calledlines, means under the control of the calling and called substations toopen the talking and operating strand circuits of said link conductorsconnected to their lines, a disconnect signal circuit associated withsaid link conductors during an established connection therewith, saiddisconnect circuit including a high resistance and closed when said lineconductor strand circuits of both calling and called lines are opened,and relays in series with said circuit rendered inoperative by saidresistance when said link conductor strand circuits of both calling andcalled lines are so opened.

35. A telephone exchange system, including telephone lines extendingfrom substations to an exchange, link conductors to connect saidsubstations and comprising sepa rate talking and operating strandcircuits individual to the respective link conductors 7 to their lines adisconnect si nal circuit asa g sociated with said link conductorsduring an established connection therewith, said disconnectcircuitincluding a high resistance and closed when said link conductor strandcircuits of both calling and called lines are opened, and the winding ofa ringing relay individual to each link conductor and the winding of acut-out relay individual to each called line, said relays being renderedinoperative by said resistance when said link conductor strand circuitsof both calling and called lines are so opened.

36. A telephone exchange system, including telephone lines extendingfrom substations to an exchange, link conductors to connect saidsubstations and comprising separate talking and operating strandcircuits individual to the respective link conductors for calling andcalled lines, means'under the control of apparatus at the calling anlcalled substations to open the talking and operating strand circuits oflink conductors connected to their lines, a disconnect signal circuitassociated with said link conductors during an established connectiontherewith, said disconnect circuit includinga high resistance and closedwhen said link conductor strand circuits of both calling and calledlines are opened, a disconnect relay, the winding of a ringing relayindividual to each link conductor and the winding of a cut-out relayindividual to each called line,

' said ringing and cut-out relays being rendered inoperative by saidresistance when said link conductor strand circuits of both calling andcalled lines are so opened, and said disconnect relay being renderedoperative when said link conductor strand circuits of both calling andcalled lines are so opened.

37. In a telephone exchange system, including telephone lines extendingfrom substations to an exchange, a cord circuit to connect saidsubstations and comprising separate talking and operating strandcircuits individual to said cord circuit for calling and called lines,means under the control of the calling and called substations to openthe talking and operating strand circuits of said cord circuit connectedto their lines, a disconnect circuit associated with said cord circuitduring an established connection therewith, said disconnect circuitincluding a high resistance and closed when said line conductor strandcircuits of both calling and called lines are opened and relays inseries with said circuit rendered inoperative by said resistance whensaid cord strand circuits of both calling and called lines are soopened.

88. A telephone system comprising a tele-' phone line terminating at acentral ofiice, a line signal for the line, a link circuit, a cut-offrelay associated with the line for controlling the line signal andactuated upon connection of the link circuit with the line, a resistancecoil, and means controlled over the telephone line for including'therein series with the relays, the inclusion of the coil serving todisable the relay asso ciated with the line. 7

40. In a telephone exchange system, the combination of a calledsubscribers line having an associated jack and relay, of a cord circuitfor interconnecting with said jack, a relay and resistance coilassociated with said cord circuit, the windings of the relays beingadapted to be placed in series when the cord circuit interconnects withsaid jack, and means controlled by the called subscriber for includingthe winding of the resistance coil in series with said relays, theinclusion of said coil serving to disable the relay associated with theline.

41. A telephone system comprising telephone line terminating at acentral office, a line signal for the line, a link circuit, a cutoiirelay associated with the line for controlling the line signal andactuated upon connection of the link circuit with the line, asupervisory relay in the link circuit responsive to the opening of thetelephone line, and a resistance coil included in circuit with thecut-oit relay upon the response of the supervisory relay to cause therelease of the cut-ott relay.

In witness whereof, I have affixed my signature in the presence of twowitnesses this 15th day of October, 1913.

FRANK M. SLOUGH.

